Clinograph



Nov. 3, 1953 L. G. P. THRING CLINOGRAPH 5 Sheets-Sheet 1 Filed Jan. 22, 1951 Inventor Zeb/ward 6. P. T/zr/ng Nov. 3, 1953 L. G. P. THRING CLINOGRAPH Filed Jam. 22, 1951 5 Sheets-Sheet 2 COSINE 9 O, 60:

Inventor Z Ha/ c/Q Enid/7 afi A itorney e. .P. THRING} CLINOGRAPH 5 Sheets-Sheet 3 Filed Jan. 22, 1951 822m m w w Inventor y Am 0 @fm 1 w p M G pm a n m X CLINOGRAPH 5 Sheets-Sheet 4 Filed Jan. 22, 1951 I nvenior 1 602mm! 6. F. Dir/n y 5%; 5W? I M Atlorney Nov. 3, 1953 L. e. P. THRING 2,657,466

CLINOGRAPH Filed Jan'. 22; 1951' 5 Sheets-Sheet 5 Inventor Z 7/316/ 6 P fir/n9 A llorney 3 an angle less than 90, for example to 60, whilst still retaining a 45 instrument. Figure 1 indicates this at G and the consequent reduction in size of the instrument is indicated by the hatched area G By adopting a 30 instrument instead of a 45 instrument a similar reduction of size is eifected as indicated by the hatched area H in Figure 2, which still shows an arrangement in which neither side of the instrument when produced would intersect the circle.

With the arrangement shown in Figure 2 the chord H subtends an angle of 60 at the centre and can be moved from a position H at an angle of to the longer side D. It could also be moved to a position H at an angle of 0 to the shorter side E without fouling a straight edge against which that side was placed, but in the first place there would then be no overlap to support the segment and secondly the range of movement so provided would still be unnecessarily great, bearing in mind the possibility of putting either edge against the straight edge and inverting the instrument.

The former difiiculty can be overcome and a further reduction of size rendered possible by restricting the extent to which movement of the segment in one direction is relied on with the short side against a straight edge. Thus in the arrangement shown in Figure 3, of the range of angles from 0 to 90, a range from 0 to 60 can be covered with the longer side D against the straight edge, by moving the chord H 30 in either direction from the position H in line with the hypotenuse to the positions H and H The remaining 30 can be covered with the shorter side against the straight edge by moving the chord 30 in one direction only, namely away from the straight edge to the position H This enables the short side to be brought into the position J and gives a further reduction in size for a given radius as indicated by the hatched area J in Figure 3.

It will be noted that in Figure 3 the inclination of the hypotenuse to the longer side is half the range of movement of the chord, thus ensuring that the overhang, and hence the remaining overlap, will be the same when the segment is in each of its extreme positions.

It still remains to settle the angle subtended by the segment at the centre of the circle, which, for a given angular range, determines how much overlap remains when the segment is in its extreme positions, and further materially aifects the size of the instrument for a given radius.

It can be shown trigonometrically that for a 30 instrument the length a of the longer side D of the instrument shown in Figure 4 is given by the equation:

where r is the radius of the arc, and is the angle subtended by the are at the centre. I

In the arrangement of Figure 3 the arc subtends an angle of 60 and with this angle the overlap in the extreme positions is 50% of the arc as hown in Figure 3. It is, however, found that this is unnecessarily great and an overlap of about is in general suflicient, making the angle subtended by the segment very slightly over 40 as indicated in Figure 4. Thus in the pre- This enables a further reduction of size to be achieved as indicated in Figure 4, in which the hypotenuse is brought down to the position K whilst the short side i further brought in to the position L, representing a total reduction of size indicated by the hatched area L Figure 4 represents the preferred embodiment of the inventionwhich is described in greater detail below with reference to Figures 6 and '7.

For the sake of greater convenience, at the sacrifice of a certain amount of accuracy for a given size, the arrangement of Figure 4 may in certain cases be replaced by the modification shown in Figure 5 in which the movement of the segment with the longer side in contact with the straight edge is only relied upon to cover the range from 0 to 45, by movement of the chord from a position K to a position hi Accordingly the range from 45 to must be covered with the shorter side in contact with the straight edge and the shorter side must be brought out to a position M in which it can be placed against the straight edge with the segment in the position K namely at an angle of 45.

In this case to ensure that the inclination of the hypotenuse to the longer side would be half the range of movement of the chord, and hence that the overlap would be the same when the segment is in each of its extreme positions, this inclination would be 22 but the proportions would then be bad and the convenience of a 30 set-square is such that it is preferred to employ an angle of 30 in this case also.

In the arrangement shown in Figure 5 the amount of overlap, and the size of the instrument for a given radius, again depends on the angle subtended by the are at the centre. The length I) of the longer side D of the instrument is in this case'given by the formula:

where r and 0 have the meanings already referred to.

In order to accommodate a single scale reading from 0 to 45 the are cannot subtend an angle than 45 and a small margin is desirable. Accordingly in a modified form of the invention the length of the instrument is given by the above formula in which the value of 20 lies between 45 and 46.

Figures 1 to 5 indicate in each case the theoretical minimum size of the instrument and in practice a small amount would in each case have to be added to provide necessary margins. In the constructions described these margins are reduced firstly by the fact that of the tongue-andgroove connection between the segment and the bearing plate the tongue is formed on the bearing plate and the groove on the segment, and secondly by the fact that the corners do not extend to the points at which the longer and shorter sides would touch the circle, so that long thin points on the bearing plate tend in any case to be avoided.

The sharp tips of the segment are cut oii to prevent accidental damage, enough being retained to allow the chord to mate with the end of the tongue of the joint carried by the bearing plate so that the hypotenuse can be formed by a continuous edge. In the construction indicated in Figure 4 and described in more detail below with reference to Figures 6 and 7, suificient may be cut off, at 60 to the chord, to allow an angle the scale to stand clear of the hypotenuse.

5. o 59 to he r ad wh n the sh rt side is seohtaet with the straight edge.

the eonstri et oh of wh ch opposite sid s a t sho hi a es hand 7 (and which 0kmsiao ls to th liaer m o l fi oite fl angu ar seal N o 3. extent is mar ed symmet iea iy on o e side of th s gment (shown in Fi ure .6) alone p rime er and is subdivided down to i hits of .1 o e en minutes. i/Vhen in the zero posit n, t zero nd o this cal ooinoieles with an index sna k P on the hearin -=p1ate.-; and nclined at at position the cho d oo he oes w h he hy otenuse, his end will eeincide with a second index P2 9. 3 the mate. Angles from 30 to 60 are read against this second index mark, the longer side 13 of the bearing la e beins e h aet with th strai ht ed e both oas st sh rte s de i oithe hear ing p e is in t o with the st a ght edg angle rom 6 to 9. are r d ih the opp s di e ti o h sam sca e a a n t t e firs ind m P1 o h h a ihe pl e- The s is numbered so that it can be read in Jooth d;i tioh without eoh i nrnier oa s place a ja t ea h nde m s. n a sho t extensi n of t e eal oi about one .el s ee ehaes se to h s d at the e t eme limit n r a in s- The a of he hea ihe p a e r vide with a ca P o sines o an es etween and 30* xte be een h tw i d x marks. ir us t nes f a e es be ween 0 and 0 b riao dir ct y f hi scal aga nst he ze o one o he egm nt ale the sine e rre pohdi e in ase to he angle reaol on the segment.

h s ne of an l s rom 0 t 0 a e r ad o a se n seale Q aeed the r rs sid o t e hearing plate as hown F u e 7, against an index mar B on t e s ment Sines of angles f om 6 o 0 re gr duated at :1 o the seg t nd r d a nst the other and Q of the scale Q on the bearing plate when the shorter d L o h latter s placed aga nst the stra ht edge.

For general use in a drawing ofiice it may be of advantage to have a simple scale reading from 0 to which is sufiicient to allow lines to be drawn in any direction, those inclined from 45 to in drawn w th h shorte e in co a t with h t aight ed e. Fo th urpose the emb im t o whioh op osite si are sho in F ur s 8 and 9 res eetiv h' (an hioh ,eorresponds to, th diagram oi. Eieore 5) the hearing plate is extended to enable the segment to clear the shorter side produced when the chord is at 45, so that either side can be placed against the straight edge for all working positions of the segment. A shoulder 53- is placed on the tongue S carried by the bearing plate to engage With a corresponding step in the recess on the segment when the chord K of the latter is inclined at 45. This allows the chord to be set at 45 without reference to the scale, enabling the instrument to serve as a 30 or 45 set-square, As shown in Figure 8 the scale T from 0 to 45 is placed on the bearing plate, thus enabling the arc of the bearing plate to be made 45 plus a small allowance necessary to allow the ends of An index mark U preferably combined with a vernier, is provided on the segment.

On the opposite face of the instrument seen in Figure 9 a scale of sines is provided, the sines of angles from 0 to 45 being in a scale V on the bearing plate and those above 45 in a scale W 6 oh the s gme t.-

is not possible to extend a scale to the pointed ends of thesegment, which are onto z s nce the sines of angles above 82 differ tron; Joy less than one per cent nd are seld m recruited, the scale can be ho t ned o ie tly to enable it to be placed a..- e p efer ed .aizt nseihent satisfies the above teou .ement an provides c ear sca e.

The se ls V of sine of ang es from .0 to 45 e at d t e b ar n plate, a d hi cled atin tettals o .0 by s ort line ex endin train the a enate ed e to a eehhuoos line at the nae-k, th s t the a es o eells w i are rouped er y extending the lin at h di-YiSiQIl- Wit .h eaeh eell eras of .9 2 or 4 9.1 ar n ao d (hot for e arity are omitted from the drawing). All the yalnes tread agains an index mark W on the seehieh-t whie oe -r sponds w t the zer one of the sta V w th h rd is parall l to the lon er steel. o t e b r ng P e- A s mi s a W o s n s of an es a ove s5 :is p ac d the se me t, a d ad a a st an index mark V1 on the bearing plate, the shorter a sl M o the l ter b in in eohtaet with t traight edgeif th sea e W e teh ied .t om end to e d of the e ment. wit a e m nt so teheihe 5, the 1. s V on the bear n p ate wou d ave o be 15 from the end o t e sta e nearer the onge shie so as o register ith the end of the scale W on he m nt when th la ter h d bee fte h h 3.0 from a pos t n K n Fi re i h the hord one o the hy ot se t a osition (K in Fi u e with e oho d parallel to the on er siole D, .Simi I y e nde W ou d be 15 f m t e end of he scale W earer to th short ide i ee the scale can t ex nd to oth nds o the se ment. the s a W i shi te h ou h 55 and the ind lihe V n the bearin Plate s moved b he s me amoun o at it l h at a point 16 15.6 from the zero of the scale V on the la t r.- Thi an e is in 5 so tha t ma k V will cr ss he b a n at s a V etwe n tw eel s- Mo o er i h er o W p ion it wi l lie eyond the end, of h e ent although it would correspond to the end of the W on the la te if i o d b a ried so ar ines oi an les ery ear nnot t e o e he read but s these dif e fr m un ty b not more than abo t -%i% this is mm t ri l The index mark W1 on the segment similarly corresponds to to an angle onthe scale W of 90 minus 16 15.6 or 73 44.4 of which the sine is .96. Therefore this mark also crosses the scale W on the segment between two cells and does not interfere with the scale. The end X of the segment nearer the short side D is preferably cut off at an angle of 45 with the chord, so that it lies parallel to the short side when in the extreme 45 position. Since the tongue S of the joint between the parts is broad at this end, it is possible to remove a considerable amount from the segment while allowing the tongue to continue the line of the hypotenuse when the chord is inclined at 30. The angular scales in both these embodiments are divided in a similar manner to the sines, each cell containing one degree while the smaller divisions of 10 .or 5

I minutes are grouped inside the cells.

What I claim as my invention and desire to secure by Letters Patent is:

1. A clinograph comprising a bearing plate and a segment together forming a complete thirty degree right angle triangle, the bearing plate having two straight sides at right angles to one another and a concave arcuate side, and the segment having a straight chord and a convex arc fitting the concave arc of the bearing plate and adapted to slide along it, angular scales being provided to indicate the inclination of the chord to the straight sides of the bearing plate, wherein the arc of the segment subtends an angle not greater than 60 at the centre, and the longer side of the bearing plate, when produced, lies just outside the circle of which the segment forms a part, whilst the shorter side, when produced, intersects that circle.

2. A clinograph as claimed in claim 1, the bearing plate having two straight sides at right angles to one another and a tongued concave arcuate side, and the segment having a straight chord and a convex grooved arc, whereof the groove fits the tongue of the concave side of the bearing plate to permit relative sliding.

3. A clinograph comprising a bearing plate and a segment together forming a complete thirty degree, right angled triangle, the bearing plate having two straight sides at right angles to one an other and a concave arcuate side, and a segment having a straight chord and a convex are fitting the concave arc of the bearing plate and adapted to slide along it, angular scales being provided to indicate the inclination of the chord to the straight sides 01" the bearing plate wherein the arc of the segment subtends an angle of not more than 60 at the center, the chord being movable from an inclination of zero to an inclination of 60 to the longer side without the segment intersecting the longer side when produced, and wherein the shorter side terminates close to the end of the arc of the bearing plate so that the chord constitutes substantially the whole of the hypotenuse.

i. A clinograph as claimed in claim 3 in which the distance of the hypotenuse of the triangle from the centre of the circle is such that the segment are subtends an angle of approximate- 1y 10 at the centre.

5. A clinograph as claimed in claim 3 in which the dimensions are such that the overlap between the segment and the bearing plate when the former is in either of its extreme positions til) is approximately a quarter of the total are of contact between them.

6. A clinograph comprising a bearing plate and a segment together form a complete thirty degree, right-angled triangle, the bearing plate having two straight sides at right angles to one another and a concave arcuate side, and a segment having a straight chord and a convex arc fitting the concave are of the bearing plate and adapted to slide along it, at least one angular scale being provided to indicate the inclination of the chord to the straight sides of the bearing plate, in which the length a of the longer side of the bearing plate is given by the formula:

a=\/3r[1-cos(30+0)l where r is the radius of the arc, and 20 is the angle subtended by the are at the centre and has a value of approximately 40.

7. A clinograph comprising a bearing plate having two straight sides at right angles to one another and a concave arcuate side, and a segment having a straight chord and a convex arc fitting the concave arc of the bearing plate and adapted to slide along it, angular scales being provided to indicate the inclination of the chord to the straight sides of the bearing plate, wherein the arc of the segment subtends an angle not greater than 60 at the center, and wherein the arcs of the segment and bearing plate are of approximately the same length and, when the segment is set to a position in which its chord is at 30 with one of the straight sides of the bearing plate, each end of the segment are approximately coincides with the corresponding end of the bearing plate arc, and wherein one of the straight sides or the bearing plate when produced lies close to but just outside the circle of which the segment forms a part whilst the other straight side of the bearing plate when produced intersects the circle of which the bearing plate forms a part.

LEONARD GODFREY PINNEY THRING.

References Cited in the file of this patent UNITED STATES PATENTS Number 

